To utilize polymerization or chain extending techniques to introduce into the backbone of copolymers of the divinyl ether-maleic anhydride type biodegradable or otherwise metabolized links and to relate this aspect of the problem to the polymer fractionation program now underway. To continue the present studies underway to incorporate into copolymers with 1,4-dienes derivatives of certain compounds of known physiological action in efforts to utilize the polyanionic character of the copolymer as a transport agent capable of delivering the active species to a pre-determined site. To attempt to show through structural studies on the copolymers an analogy between their polyanionic character and the polyanionic character of naturally occurring polymers such as RNA and DNA; also, to introduce into the copolymer certain substituent groups such as phosphoric acid moeities, purine or pyrimidine moeities, and/or nucleoside units in an effort to further simulate the structure and physiological action of these natural polymers. To continue the fundamental studies of factors which control the order of incorporation of monomers into the copolymer chain, and to utilize this information in planning syntheses designed to yield copolymers which simulate natural polymer structure and physiological action.